The present invention relates to a device for adjusting the depth of a vehicle seat, in particular an automobile seat.
DE 41 04 440 C2 discloses a known seat depth adjusting device. In this known device, a flexible cushion part that is made as a one-piece cushion is provided with a continuous upholstered surface. The front portion of the flexible cushion rests upon a support member that is slideable for adjusting the seat depth. Depending on the desired seat depth, the front portion of the cushion is bent more or less over the front edge of the support member, with a spring compensating for the travel and providing the necessary tension. This seat depth adjusting device prevents a so-called crumbling fold. A crumbing fold occurs when separate cushion parts are present without a continuous upholstered surface.
One aspect of the present invention is an improved seat depth adjusting device. In accordance with this aspect, a seat part having an adjustable depth includes separate front and rear cushion parts. The front cushion part is mounted for being movable relative to the rear cushion part for adjusting the depth of the seat. The seat part further includes a cover extending over both the rear cushion part and the front cushion part. The cover is mounted so that it serves as a continuous, exterior upholstered surface extending over both the rear cushion part and the front cushion part. In accordance with one aspect of the present invention, a vehicle seat is provided. The vehicle seat includes the above-described seat part and a seat back positioned at a rear edge of the seat part.
Because the front cushion part and the rear cushion part are made separate from each other, it is relatively easy to move the front cushion part for adjusting the seat depth. In accordance with one aspect of the present invention, the front cushion part contacts the rear cushion part and deflects (e.g., bends) as it is moved relative to the rear cushion part. As a result of the deflection, the front cushion part undergoes no squeezing in the region of the front edge of the seat part. Advantageously, there is significant latitude in the selection of the thickness of the cushion parts, and manufacture can be relatively simple and cost favorable. As an additional advantage, a crumbling fold is prevented by the common cover.
In a preferred embodiment, the front cushion part is rotatable relative to the rear cushion part. This has the advantage of a simple manufacture and assembly. For example, the front cushion part can be rotated via a drive unit with a longitudinally displaceable push bar, which engages the front cushion part preferably off-center, i.e., approximately in the fashion of a connecting rod. In combination with a noncircular front cushion part, this causes a rotational movement, during which the front cushion part is moved forward and back over different distances. Due to the lever arm conditions, the off-center engagement of the drive with respect to the axis of rotation has the advantage that the drive force is smaller than, for example, in the case of a drive via a shaft in alignment with the axis of rotation.
In a further preferred embodiment, the front cushion part is arranged on a profiled base support, which has for example, a substantially triangular cross section, namely a cross section with rounded corners and bent sides. This base support preferably has a supporting mechanism mounted to one of the corners, and the drive unit, with its off-center engagement, is joined to the base support in the region of another one of the corners. In accordance with one example, a corner or a side of the triangle is oriented upward toward the cover at the smallest or greatest seat depth, and the triangle is rotated between the smallest and greatest seat depths. The front cushion part has on its upper side a different length as a function of the position of the triangle. In all positions, the two cushion parts are so close together that the upper seat surface that is provided by the upholstery material is supported by the cushion parts over substantially its entire length.
In accordance with one aspect of the present invention, material with little friction (for example, nonwoven/leather) is paired between the cover and the front cushion part for purposes of keeping frictional forces low during the movement of the front cushion part relative to the cover, namely for purposes of not having to overdimension the force that is to be applied by the drive unit. So that the cover remains taut and does not pucker, and for purposes of compensating for the amount of the cover that is needed when the seat depth is enlarged, it is preferred to provide an elastic adjusting element, for example, a rubber band or a spring. In the case of greater adjusted depths, it is preferred to cause the elastic adjusting element to follow, for example, the mounting point of the adjusting element by a corresponding kinematic motion.